The present invention relates to modules and associated apparatus operable to monitor characteristics of wheels and/or their associated tyres; for example, to a module and associated apparatus for monitoring characteristics of wheels and/or their associated tires and conveying information indicative of these aforementioned characteristics via a communication link to an electronic control unit (ECU) and/or control system, for example for user-display. Moreover, the present invention also concerns methods of monitoring characteristics of wheels and/or their associated tires. Furthermore, the present invention also relates to software and software products executable on computing hardware for executing these aforesaid methods.
Tyres, also known as “tires” in American-English, are critical components in road vehicles. Contemporary tires not only ensure adhesion of their associated road vehicles to road surfaces in widely varying weather conditions, but also perform vibration and shock isolation functions. Moreover, during their operating lifetime, tires are required to survive potentially up to several thousand or even millions of deformation cycles without exhibiting work-hardening failure, and yet exhibit a relatively modest degree of energy dissipation therein as a result of viscous dampening effects. As an additional operating requirement, contemporary tires need to be robust against scuffing and objects impacting thereonto. Yet further, tubeless tires are required to robustly grip onto their associated wheel hubs even when subject to considerable stresses, for example during emergency braking. In response to these aforementioned requirements for contemporary tires, the tires are constructed from elastic synthetic rubber, natural rubber and/or plastics material reinforced by meshes of metal wire, carbon fibre and similar. Modern tires are therefore to be respected as highly optimized and advanced products.
Tire failure during operation can potentially result in immobilization of an associated vehicle or even accident. Moreover, tires operated at unsuitable pressures can adversely influence associated vehicle fuel economy; fuel economy is becoming increasingly pertinent in view of increases in fuel costs as well as in view of carbon dioxide generation and its perceived impact on World climate change.
It is known to mount sensors onto automobiles to monitor characteristics such as tire pressure and acceleration in one or more orthogonal axes, and to convey information representative of these characteristics via wireless communication links to electronic control units (ECU) forming parts of data management systems of the vehicles. By employing such arrangements, it is possible to warn drivers of a need to inflate one or more tires of their vehicles in order to improve driving quality and safety.
In a published Japanese patent no. JP 2003211924 (Mazda Motor), there is a disclosed a pneumatic sensor device suitable for use with a tire of a vehicle for detecting tire pressure and generating corresponding tire pressure information. The device includes a transmitter for transmitting the pressure information together with an identification code for distinguishing the sensor device from other such sensor devices simultaneously included on other wheels of the vehicle. A control unit of the vehicle is operable to receive the transmitted pressure information and its associated identification code. The received pressure information is stored in a memory of the control unit. The control unit is operable to raise an alarm in an event that tire pressure is not correct pursuant to predefined criteria.
In a published United Kingdom patent application no. GB 2385931 A, tire monitors are described which are mounted adjacent to tires near their tire inflation valve stems. The tire monitors include sensors to measure pressure, temperature and rotation direction of their respective tires. Moreover, the monitors are operable to communicate measured sensor signals via transmitters to their respective receiver for subsequent processing and eventual presentation on a display unit. A vehicle mounted controller in communication with the receiver is operable to determine whether pressure information is associated with a front tire or a rear tire based on the strength of the wireless signal received at the receiver, and whether pressure data is associated with a right tire or left tire based on associated rotation direction data.
A technical problem arising for fleet operators of vehicles is that wheels and tires of their vehicles are subject to maintenance events at various points in time. For example, there is a requirement in Northern Europe and Canada to seasonally switch between summer and winter tyres; such switch is usually achieved by exchanging wheels rather than removing tires from wheel hubs. However, wheels are removed from vehicles for other purposes, for example for puncture repair or replacing worn tires on wheels hubs. With such changes occurring, it is difficult for fleet operators to maintain an up-to-date record of conditions of tires on their vehicles and processes to which the wheels of their vehicles have been subjected. Owners of vehicles with defect tires can be subject to penalties from road authorities; such penalties are potentially mitigated when it can be shown that vehicle owners have used all endeavours to ensure that their vehicles are in good operating order. Moreover, it is within an interest of fleet operators that wheels and associated tires of their vehicles are in good order in order to avoid a proportion of time that vehicles are not in use and not earning money.
A technical problem addressed by the present invention is therefore to provide a more advanced wheel and tire monitoring apparatus and modules. Moreover, the present invention seeks to provide such wheel and tire monitoring apparatus and modules in a manner better suited, for example, to the requirements of commercial fleet operators; such fleet operators can, for example, include heavy commercial vehicle fleet operators, taxi fleet operators, and automobile leasing and hiring enterprises.
It is desirable to provide an improved wheel and/or tire monitoring apparatus and module which are capable of enhancing safety and reliability of vehicles, and also detecting tampering of wheels of vehicles.
According to a first aspect of the invention, there is provided a module operable to monitor at least a pressure (P) within a tire of a wheel, said module being operatively mounted to said wheel, said module includes:    (a) a pressure sensor for measuring said pressure and generating a corresponding pressure signal; and    b1) an associated data memory including a data field containing data relevant to the functional status of the tyre;            characterised in that        said module includes a flag which can be set by a data processor to represent “VALID” or “INVALID” for denoting validity or invalidity of said data relevant to the functional status of the tire and that said flag is set to be changed from “VALID” to “INVALID” as soon as said pressure (P) measured by said pressure sensor falls below said predetermined threshold value.        
The invention is of advantage in that the module is capable of providing enhanced monitoring of operation of the at least one wheel, thereby enhancing safety and reliability, by monitoring wheel characteristics.
By the inclusion of a flag that can be set by a data processor to represent “VALID” or “INVALID” for denoting validity or invalidity of said data relevant to the functional status of the tire and that said flag is set to be changed from “VALID” to “INVALID” as soon as said pressure (P) measured by said pressure sensor falls below said predetermined threshold value. It is possible for the operator to ensure that data relating to a specific tire is valid as long as it is attached to a specific wheel under the condition that a pressure loss exceeding the threshold value has not occurred. A loss of pressure exceeding the threshold value would indicate that the tire has been removed from the rim, that the tire has been used at pressure well below the operating pressure or that a puncture has occurred. Since, if any of these events have occurred, tire data can not be guaranteed because the tire may have been changed or the properties of the tire may have deteriorated due to puncture or excessive wear following use of the tire at an inappropriate pressure.
By thus monitoring the pressure and setting a flag indicating that the pressure has been kept above an intended pressure level it can be assured that data relevant to the functional status of the tire is valid. An on board system may therefore rely on the tire data stored in the associated memory and therefore adapt subsystems of the vehicle, such as application of braking forces for instance, to the data contained in the associated memory. In the event the data relating to the relevant to the functional status of the tire is classified as invalid, an on board system will adapt its function to default values assuming an inferior tire quality.
In order to ensure that the flag is not changed as soon as the pressure in the tire is refilled without verifying tire data by inspection, the data processor is prevented to change said flag from “INVALID” to “VALID” unless a key code signal is received externally from the module. However, after having verified tire quality by inspection, tire data can be reset to status “VALID” from status “INVALID”. This may thus be done by said data processor upon reception of a key code signal is received externally from the module.
By these measures the validity of data relevant to the functional status of the tire can be ensured and it is safe to adapt subsystems of the vehicle to said data.
The invention furthermore relates, according to aspects thereof, to a method of validation of data relevant to the functional status of a tire stored in a module mounted in a wheel, and a method of detecting misuse of tires wherein a data processor is operable to continuously or periodically update data stored in a data field containing data relevant to the functional status of the tire, in which method validation of the data relevant to the functional status of the tire is performed by such a method.
Features of the invention are susceptible to being combined together in any combination without departing from the scope of the invention as defined by the appended claims.